But, attention should be given to the weld area between the outside weld
seam and the flange's weld joint. for the flanges - I prefer the welding
to be done from outside-full penetration as well. If necessary a
rim-like feature can be machined to the flanges.
The reason for full penetration welding is to eliminate any clevises,
which will accumulate grim during the manufacturing/UHV cleaning process.

For a piece this size a vacuum braising oven will be difficult to find.

I would appreciate if I have the latest set of drawings for a review of
the manufacturing process.

George,
OFHC (oxygen free high conductivity) copper is regarded as a UHV
compatible material, but this is for solid metal, not electroplated.
Dimo and I spoke about the finish of electroplated copper and are not
convinced that it is suitable for 10-8 vacuum. I will look into
databases from other institutes to see if they have information on
electroplated Cu, and what the limitations are. As an aside, has vapor
deposited Cu been examined?
We think that a better choice would be for a solid OFHC copper chamber.
It meets vacuum, magnetic and structural requirements. It will be more
expensive than aluminum, but will eliminate the process of
electroplating. Machining would be similar to aluminum, welding may
also be of similar cost. Yield strength is lower, so the chamber would
have to be thicker. Explosion bonded Cu-304L flanges are available.
I will do further research on electroplating of Cu.
Geoff
On 28/04/2016 1:33 PM, George Clark wrote:

Geoff
Could you write to us about the vacuum
qualities of Copper.
regards
George
-------- Forwarded Message --------
Subject: Re: copper plating of vacuum chamber
Date: Thu, 28 Apr 2016 12:45:30 -0700
From: Marco Marchetto <marco@triumf.ca>
To: Friedhelm Ames <ames@triumf.ca>, George Clark <gsclark@triumf.ca>
Friedhelm,
I think this is a very good alternative, a (most likely) cost
effective way to mitigate the risk of going with an aluminum chamber.
Marco
On 4/28/2016 12:36 PM, Friedhelm Ames wrote: